This invention is directed to flame-retarded acrylonitrile-butadiene-styrene copolymer compositions comprising bis(beta-pentabromophenoxyethyl) succinate.
Highly brominated compounds such as the tetrabromophenyl ethers and perbrominated biphenyl compounds are well-known flame retardants for a variety of thermoplastic resins. Although the flame retarding behavior of such compounds is adequate for many materials, the tendency to migrate and to be exuded from the resin during processing, particularly where the compounds are employed at high concentrations in the resin, are distinct disadvantages. Methods in the art for overcoming the tendency of flame retardants to migrate during processing have included incorporating the brominated moiety into a polymeric structure, such as by grafting a bromine-containing molecule onto an existing substrate, by directly brominating the substrate or by copolymerizing a suitable bromine-containing monomer in the preparation of the thermoplastic. As an alternative, flame retardant molecules have been sought which possess an appropriate combination of solubility in the thermoplastic resin, adequate stability at resin processing temperatures, and sufficient ability to retard burning without resort to an inordinately high concentration in the resin. As will be appreciated by those skilled in the art, the great proliferation of compounds available for use as a flame retardants has come about in part because no single compound possesses a balance of these characteristics that is adequate for use in every thermoplastic resin. Most flame-retardant compounds are known to be useful in a very limited class of thermoplastic resins, and the search for compounds having more effective balance of characteristics continues.